Benign by Design Chemistry - ACS Symposium Series (ACS

Chapter 1 Benign by Design Chemistry Paul T. Anastas

Downloaded by BROWN UNIV on May 8, 2016 | http://pubs.acs.org Publication Date: November 18, 1994 | doi: 10.1021/bk-1994-0577.ch001

U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics, Mail Code 7406, 401 M Street, Southwest, Washington, DC 20460

The role of the synthetic chemist is crucial toward meeting the goals of both environmental protection and economic growth. The principles for the discovery, evaluation and development of environmentally benign alternative synthetic pathways have been investigated and applied both in basic research and in commercial practice. The principles of pollution prevention will be playing an increasing role in the routine work of the synthetic chemist in the future and each chemist will need to know how to design syntheses that are more environmentally benign in order to increase the chances of commercial viability of the methodology.

The synthetic chemist has generally not viewed him/herself as having a role in environmental chemistry. The message of Benign By Design chemistry is that the role of synthetic chemists is fundamental to environmental concerns and to pollution prevention. While the traditional areas of environmental chemistry, such as analytical and atmospheric chemistry, will always play an important role it is crucial that the synthetic chemists (who have been perceived as being responsible for much of the toxic pollution that exists) now be associated with the avoidance of environmental problems. It is essential from an environmental and economic standpoint that pollution prevention become the paradigm of first choice in the area of chemical production. Synthetic chemists are the only ones capable of instituting this fundamental change. What is Pollution Prevention? The United States's approach toward dealing with environmental problems has evolved since the early stages of the environmental movement in the 1960s and early 1970s. Most approaches have centered around the "command and control" approach to pollution. In its earliest form this involved the government allowing potential releasers of toxic substances to release materials only in certain limited 0097-6156/94/0577-0002$08.18/0 © 1994 American Chemical Society

Anastas and Farris; Benign by Design ACS Symposium Series; American Chemical Society: Washington, DC, 1994.


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amounts and/or requiring them to obtain permits to dispose of toxic chemicals, often to air or water. At the time, this tactic was described by the rather black-humor rhyme, "Dilution is the solution to pollution." As the environmental movement progressed, it became more common for the government to require treatment of various wastes prior to their release to the environment. Usually this involved sufficient treatment techniques such that the concentration of the toxic substance was reduced to an acceptable level. It is only within the last several years that the U.S. approach to dealing with pollution has been not to create the polluting substances in the first place. This is the basis of pollution prevention. Pollution prevention as an approach to environmental problems is analogous to preventative medicine as an approach to medical problems. It is commonly accepted that it is preferable to avoid getting a disease rather than to have to cure the disease. It is equally logical and intuitive that avoiding environmental problems is far preferable to having to cure them. Both of these adages hold for many of the same reasons to both the patient and the environment: minimize pain and suffering, avoid long term systemic damage caused by the initial insult and reduce costs of sustained viability. The costs of the command and control approach to environmental problems are staggering. Estimates of how much business is spending on control and treatment technologies are as high as $115 billion dollars annually (1). Still with all of this money invested in pollution control, over three billion pounds of waste were released to the environment in 1992, as shown in Table I, according to the U.S. E P A ' s Toxic Release Inventory (2), which has tracked the release of only approximately 300 chemicals. Since over 70,000 chemicals are currently in commerce in the United States (7), it is easily seen that despite efforts of regulatory agencies to control the release of chemicals to the environment, they are only capable of focussing on those few of highest priority. Most of these documented chemical releases have been to the air as shown in Figure 1. It is certainly desirable for industry to reduce its operating costs associated with the compliance with local, state and federal regulations, waste treatment and waste disposal. By focussing on reducing the amount of waste that is generated, a company will be able to achieve economic benefits associated with avoiding these operating costs. This type of economic incentive is encouraging companies to look inward to find ways to regulate themselves and reduce their environmental releases. The private sector is finding that pollution prevention makes good business sense as evidenced by the examples of the Dow Chemical Corporation's W R A P Program (Waste Reduction Always Pays) (3) and 3M's 3P Program (Pollution Prevention Pays) (4). It is revolutionary in the fullest sense of the word when environmental stewardship is transformed from being perceived by industry as an economic burden to being perceived as necessary for increased profitability and competitiveness. This is the fundamental difference between pollution prevention and the previous command and control approaches to dealing with environmental problems and this is why there is the promise of profound effectiveness with this approach.


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Table I.

TRI Chemical Releases


1992 Releases

Pounds

Total Releases

3,181,646,757

Air Emissions

1,844,958,336

Surface Water Discharges

272,932,953

Underground Injection

725,946,415

Releases to Land

337,809,053

SOURCE: U . S . EPA, TRI Annual Report, 1992

Figure 1. Releases of TRI Chemicals to Various Media SOURCE: U . S . EPA, TRI Annual Report, 1992


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In 1990 the U.S. Congress passed legislation to promote pollution prevention as the basis for environmental policy in the United States. In the Pollution Prevention Act of 1990 (5), pollution prevention is defined in terms of source reduction. Source reduction is defined as: Any practice which reduces the amount of any hazardous substance, pollutant, or contaminant entering any waste stream or otherwise released into the environment (including fugitive emissions) prior to recycling, treatment, or disposal; and reduces the hazards to public health and the environment associated with the release of such substances, pollutants or contaminants. The term includes equipment or technology modifications, processes or procedure modifications, reformulation or redesign of products, substitution of raw materials and improvements in housekeeping, maintenance, training, or inventory control. It was through this statute the U . S . E P A was first mandated to pursue pollution prevention solutions in all of its environmental protection initiatives. The Administrator of the E P A , Carol Browner has cited pollution prevention as E P A ' s "central ethic" and has encouraged its incorporation into all future environmental regulations (6). Some of the earliest environmental laws to incorporate pollution prevention were passed by state legislatures. States such as Massachusetts and New Jersey promulgated laws which instituted provisions for "toxic use reduction" in efforts to minimize the degree to which hazardous substances are employed at various stages of manufacturing, processing and use of chemical products (7). Early Approaches to Pollution Prevention When the concept of pollution prevention first was introduced as an approach to environmental problems, the majority of its early manifestations were in the form of housekeeping solutions. Reducing leakages in piping systems, covering vats and vessels which hold volatile substances to reduce evaporation, reducing loss of material through over-spray in spraying applications were some of the earliest pollution prevention practices. Many of these process changes resulted in significant reductions in waste and pollution at the source. Materials which otherwise would have been treated or disposed of could now be used profitably. While solutions such as these seem in retrospect simple common sense, they were none-the-less, changes in standard operating procedures for many companies. Many of these early approaches to pollution prevention are what could be described as the "low-hanging fruit: " in other words, those solutions which are fast and easy to implement. The potential for pollution prevention, however, is far more fundamental. It requires a change in the manner in which products and processes are designed from their inception. Without question, all approaches toward preventing pollution should be assessed and implemented wherever possible. This chapter, however, will focus on the earliest design phase of chemical manufacture, the design of the synthetic sequence.


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The Future of Pollution Prevention As the familiarity with the concept of pollution prevention increases throughout the scientific and industrial community, source reduction is being considered at earlier and earlier stages of the life cycle. Products and processes are going to need to be designed such that they do not generate waste in the first place. Even the lack of waste generation alone is not enough; products must be designed such that they do not use, either in their manufacture or use, hazardous substances. By eliminating a demand for the use of substances of this type there will be a multiplying affect on the environmental benefit of these new design procedures. These choices must be made after careful analysis of the trade-offs that need to be made in the decision of how to synthesize a new chemical substance. While it is easy to state, correctly, that it is imperative to minimize the use and generation of substances which pose a hazard to human health or the environment, only those individuals qualified to fully understand the nature of the choices can be relied on to make those choices responsibly. This is precisely why the synthetic chemist will play an increasingly important role in allowing the chemical industry to discover and commercialize technical innovations. These innovations will need not only to maintain and improve on the quality of current products but also to develop new synthetic methods for these products to be made in a less costly and environmentally responsible manner. These principles will need to be built into the development protocols of new chemical products as well. How Does Pollution Prevention Relate to the Synthetic Chemist? To fully appreciate the fundamental role of the chemist in pollution prevention, we need to gain historical perspective and ask, "How have synthetic chemists traditionally designed and evaluated chemical syntheses for the manufacture of chemical products?" Over the years, chemists have repeatedly demonstrated their expertise to identify, understand and solve problems. In everything from pharmaceuticals to plastics, chemists have developed new methods and materials which have advanced society in countless ways. What is beginning to be recognized within the scientific community is that synthetic chemists will need to focus attention on ways of preventing environmental problems as effectively as chemists in general have been at solving them (8-17). The Importance of Yield. One of the primary criteria for evaluating a synthetic transformation or an entire synthetic pathway in the manufacture of a chemical product is the yield of the process. Yield, simply stated, is the percentage of product obtained versus the theoretical amount one could have obtained for a given amount of starting material. This evaluation tool has been used historically because it is sound from a scientific as well as an economic perspective. From a scientific point of view, yield can be a good indicator of thermodynamic favorability of a particular process when evaluated in the context of the reaction or manufacturing conditions. From an economic point of view, yield is, of course, important as an indicator of the efficiency of use of the feedstocks. If the yield is low, other economic or technological factors must be considered or alternatives pursued to


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ensure that the inherent inefficiency doesn't result disadvantageous situation for the manufacturer.

in an economically

The Importance of Feedstock Cost. Historically, the decision about which way to make a particular chemical substance would hinge on the selection of a feedstock or feedstocks. If there were a feedstock that was readily available and inexpensive, the synthetic methodology employed in the manufacturing process would usually reflect that economic logic. There is no doubt that the selection of feedstocks based on cost and availability and the use of yield in evaluating a synthetic scheme are always going to play an important role in the world of chemical manufacture. It is now the case, however, that these will no longer be the only criteria by which to judge a synthetic method. How Has the World of Chemical Manufacturing Changed? Since the time immediately following World War II when the chemical industry in the United States began to emerge as a dominant industrial sector, there have been significant changes in the societal values and the business climate of the United States. The same industry, the chemical industry, that was once hailed as the provider of modern convenience and innovation, now is associated with fouling the planet. To some degree these sentiments are justified by examining which industries are releasing the majority of toxic substances to the environment as shown in Figure 2. With these social opinions in place, laws soon followed which reflected the popular attitudes. The results of these statutes have effectively required a chemical company to consider additional factors when designing, producing and selling a chemical product. These considerations are listed in Table II.

Table Π. Considerations of Costs of Chemical Manufacture OLD Feedstock Price/Availability Energy Costs

NEW Feedstock Price/Availability Energy costs Regulatory compliance costs Waste disposal costs Waste treatment costs Liability costs Green marketing Consumer backlash


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CHEMICALS PRIMARY METALS PAPER PLASTICS

Ρ b TRANSPORTATION EQUIP, g

FABRICATED METALS

5

PETROLEUM


FURNITURE ELECTRICAL PRINTING

Billions of Pounds

Figure 2. Top Ten Industries for Total TRI Releases, 1992 SOURCE: U.S. EPA, TRI Annual Report, 1992 COSTS

Waste Treatment

Waste Control

Regulatory Compliance

Energy

Feedstocks

—ι

1940s

1

1950's

1

1960"s

1

1970's

1

Ï

1980's 1990's

TIME

Figure 3. The Changing Costs of Chemical Manufacturing


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Why is the Role of the Chemist Fundamental to Pollution Prevention? In moving toward a society that is geared toward instituting pollution prevention principles on a national level, it is imperative that there be a consideration of how chemicals are made. This includes a consideration of the individual synthesis or the entire synthetic sequence involved in the synthesis of a chemical substance. Since the beginnings of the scientific approaches to chemistry, chemical synthesis steps and their mechanisms have been the primary focus of chemists. Historically, and into present times, the most important criterion for selection of one synthetic step in the formation of a chemical versus an alternative in small scale synthesis has been which one had the better "yield." (In the case of industrial synthesis both yield and cost of starting materials had been important determinants as mentioned above.) Using this criterion, thousands of synthetic chemical reactions have been studied and reported in the scientific literature. This collection of synthetic transformations is what the synthetic chemist uses when designing how to make a particular compound or how to add a particular functional group onto a compound. From a scientific standpoint, the use of yield as a criterion was kinetically and thermodynamically sound and in most instances it was favorable from an economic standpoint as well. In view of the new emphasis on pollution prevention both by regulatory agencies and the chemical industry and the skyrocketing costs of waste disposal, waste treatment, and regulatory compliance, the evaluation scheme of judging the choice of a particular synthetic method based on the concept of maximum yield as the sole driving economic force is no longer valid. It is beginning to be recognized that it is possible to change the way that chemicals are made by changing the manner in which individual synthetic transformations or overall synthetic schemes are selected to make a chemical compound. These new methodologies can be designed so that they are intrinsically more environmentally benign. In large part, many of the basic synthetic methodologies are developed in academic laboratories and in those chemical companies large enough to have significant chemistry research and development departments. Pursuing this area of benign chemistry research will provide the chemist with more "tools" or synthetic methodologies to select from when integrating pollution prevention into a manufacturing process. This area of research meets both the chemical industry's and society's needs in developing the concept of pollution prevention and the academic community's need to focus on basic research. The next generation of synthetic chemists will certainly be focused on how to build new chemical structures but they will also be incorporating all of the impacts, scientific, economic and environmental, into their selection of how to make the chemical product. The moment that a chemist puts pencil to paper to design how a chemical product will be made, he/she is intrinsically making decisions about: • What hazardous wastes will be generated, • What toxic substances will need to be handled by the workers making the product, • What toxic contaminants might be in the product, • What regulatory compliance issues there are in making this product,


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• What liability concerns there are from the manufacture of this product, and • What waste treatment costs will be incurred. By putting forethought into the selection of the method of making a chemical product such that all of the scientific, environmental, and economic impacts of a particular process are considered, the synthetic chemist can have perhaps the most influence in achieving pollution prevention.


What is Benign By Design Chemistry? Benign By Design chemistry defines synthetic elegance on the basis of three factors: • Efficiency of synthetic methodology • Economically viable • Environmentally Benign The concept of synthetic efficiency has been discussed in terms such as carbon economy and atom economy (18). Both of these concepts poignantly illustrate the desirability of the incorporation of all of the atoms used in the transformation of the starting materials into the product. While full incorporation of atoms will never be achieved in all synthetic methodologies, it should be used as a goal and as one criterion by which to judge the benign nature of a reaction or reaction scheme. Economic viability, simply stated is a pass/fail test for commercialization of a process to manufacture chemical products. If the synthetic technology cannot survive economically, the other virtues of the method quickly become irrelevant. It must be remembered, however, that the economic analysis must make sure to take into consideration all costs related to the manufacture such as those listed above (e.g., waste disposal, regulatory compliance, etc.). Without factoring in these significant related costs, it would be easy to incorrectly dismiss a new, more environmentally benign methodology as not being cost competitive (Figure 3). What are the new considerations in designing a new synthetic pathway for the manufacture of a chemical product? As has been discussed above, one can no longer consider just the yield and cost of feedstocks when selecting a synthetic route to the manufacture of a chemical product. Synthetic chemists and decision makers need to ask the following questions: What are the Toxicity Impacts of the Manufacture to Humans? This analysis must include all substances related to the synthesis. Toxic endpoints should include not only lethality (LD ), but also endpoints such as neurological disorders, reproductive and developmental effects, etc. 50

What is the Impact on the Living Environment? Considerations of direct toxicity to various plant life and wildlife should be included whenever possible. What is the Impact on the Larger Environment? The "larger environment" would include the effects such as stratospheric ozone depletion, atmospheric ozone


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generation, greenhouse gas generation, acidification and/or deoxygenation of lakes and streams, etc. Will This Increase the Potential for a Chemical Accident? While very often pollution prevention and accident prevention work hand-in-hand to minimize the risk to human health and the environment, this is not always the case and cannot be assumed without an analysis.


What Aspects of the Synthetic Scheme Need to be Evaluated for Whether It L· Environmentally Benign? For many years, much of the focus of the environmental movement and specifically the regulatory agencies was concentrated on the chemical products that the chemical manufacturers were producing to ensure that they did not pose a risk. Now the focus is no longer just the final product but all of the substances associated with the manufacturing process. A few of the materials to be considered are listed below. -

Feedstocks Reagents Reaction Media By-products and Impurities Catalysts Separation Solvents Distillation Products

Approaches to Benign By Design Chemistry Academic Research. There has been a significant amount of activity in the area of Benign By Design chemistry in recent years. While it is definitely an area of investigation in its infancy, it is also being recognized as providing rich opportunities for new basic research in the academic community. Some of this research is being developed and pursued with the goals of pollution prevention and designing environmentally benign synthesis in mind. Other research projects have been pursued in years past and are now being recognized as having significant technological advantages which make them more environmentally benign than alternative techniques. An example of the latter is the work in stereoselective reaction schemes, including chiral catalysis. This has been an active area of research for decades for a variety of good reasons. A n additional good reason is that by making only the enantiomer that is desired from an otherwise racemic mixture, one is preventing the wasteful production of an equal amount of useless product. Work in general catalysis, biomimicry, and solid state chemistry has been pursued previously with a variety of goals and objectives to which now can be added environmental benefits. Several areas of research have been more thoroughly investigated for their application in Benign By Design Chemistry than others.


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Computer Design of Synthetic Methodologies. Over the past twenty-five

years, the concept of developing and using computer software to design synthetic transformations or entire synthetic pathways has been attempted by a number of different research groups (19-22). Some of these computer programs work through use of databases, some by heuristic logic programs and some through the use of artificial intelligence. These programs may be very specific to certain reaction types or may be very general and may work in the synthetic or retro-synthetic direction. Until recently, however, there has not been a consideration of environmental impacts in the evaluation schemes to choose one synthetic transformation over another. The U.S. EPA has embarked on a project to promote the incorporation of environmental considerations into the major software programs as well as the development of new software to design environmentally benign syntheses (23). Solvent Alternatives. The environmental consequence of using organic solvents in the manufacture of chemical products has been an issue of concern for many years. The new Clean Air Act Amendments (CAAA) (24) have listed many commonly used volatile organic compounds (VOCs) which are used as solvents as hazardous air pollutants. A number of research projects are on-going with the goal of reducing the amount of VOCs used and released by the chemical industry. One active area is in using super-critical fluids (SCFs) as a reaction medium. While the usefulness of SCFs as an extraction solvent, a cleaning solvent or in analytical methodologies has been well-established, the use of super-critical carbon dioxide as well as other SCF's is a far less explored area of research. There have been recent successes documented in the use of SCFs as a reaction medium for polymerization reactions (25), free-radical transformations (26), and in certain catalytic transformations (27). One approach toward solvent alternatives to VOCs is the increased use of aqueous reaction systems. There have been a number of investigations on conducting synthetic transformations in water which have previously only been carried out routinely in organic solvents (28). With the goal of VOC solvent reduction outlined by both the environmental movement and the regulatory community, an obvious approach to dealing with the problem is through the greater use of solventless and solid state chemistry. Neat reactions have the obvious advantage of not generating any waste solvent that needs to be incinerated, disposed of or recycled while solid-state chemistry has the additional advantage of having a very low vapor pressure. The low vapor pressure decreases the exposure of workers to any hazard that may exist through inhalation, thereby reducing therisksoverall. Alternative Feedstocks. One area to address when evaluating a synthetic transformation or a synthetic pathway to assess whether or not it is environmentally benign is what materials are being employed at the front-end, the feedstocks. By using substances which either reduce or do not possess significant hazards to human health or the environment, the synthetic chemist is reducing the overallriskof the manufacturing process. There are several areas that are prime areas for research on benign feedstocks.



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For a number of years, there has been research in the area of using "masked synthons" in synthetic schemes to achieve difficult transformations. These synthons could be designed to withstand reaction conditions otherwise unfavorable to the parent functional group but still serve as the synthetic equivalent in order to accomplish the synthesis. Using this same logic, it is possible for a masked synthon to be used in order to make the chemical, which must be handled by individuals involved in the manufacturing process, less toxic. Small structural changes in a feedstock can reduce the toxicity of the substance by orders of magnitude while still allowing the synthetic equivalent to be generated in situ. The vast majority of the chemical products produced in the United States today are ultimately derived from petroleum feedstocks. While there are petroleum feedstocks that should be recognized as being environmentally benign, there are many others that are quite hazardous such as benzene, a known carcinogen. It is for this reason that there is research being conducted on alternative feedstocks to petroleum such as biological starting materials (29-30). Examples of the potential applications of biological feedstocks are shown in Figure 4. Biological feedstocks provide several advantages including the fact that they are derived from renewable sources. In addition, most petroleum products are in a highly reduced state and need to be oxidized in order to instill the type of functionality necessary for further product development. Oxidation processes can have pronounced environmental impacts, especially those which employ the use of heavy metals. In contrast, biological feedstocks are often highly oxidized and highly functionalized which, generally, allows for cleaner types of transformations such as reductions. Alternative Catalysis. Catalysis has the promise of making an increasing number of chemical manufacturing processes not only more efficient, but also more environmentally benign. There has been investigation into new applications of nontraditional catalysts to reduce the environmental impacts of certain reaction types. The Friedel-Crafts reaction is a widely used synthetic methodology which classically incorporates the use of a Lewis Acid catalyst as a part of its mechanism. Kraus (31) has carried out research in the area of producing "Friedel-Crafts-type" acylation products using light as a catalyst. Other work on the cleavage of dithianes has been performed by Epling's group (32). Their methodology changes the typical "reductive cleavage" methodology which uses heavy metals as catalysts and uses visible light with a dye in order to affect the cleavage. Industrial Initiatives Catalysis. One important area of investigation that is being vigorously pursued by the chemical industry is catalysis. Certainly, catalytic processes can offer many advantages, one of which is making the process more environmentally benign in many cases. The work being carried out by Catalytica (33) and Chemical Contractor Ltd. (34) in designing new catalysts which have the net effect of decreasing the environmental impact of a chemical process is illustrative of the work that is being done.



Fast Pyrolysis

AqueousJ Fraction

Solvent Separation

ACETIC ACID

P/N Oils

J Gases I

' BTX

[Olefins k

c

ZSM-5 Catalysis

Zeolite Catalysis

LEVOGLUCOSAN

BTX


PHENOLICS

ANTHRAQUINONE

RESORCINOL PERACETIC ACID

MIXED ACIDS

HYDRO XYACETALDEHYDE

PHENOLICS

TOLUENE XYLENE

BENZENE

COPRODUCTS

PENTANES, PENTENES

BUTADIENE


Figure 4.

I Clean I Fractionation

•XYLOSE

L_

•GLUCOSE

•FURFURAL

, LACTIC ACID

Flowchart for Production of Chemicals Available from Renewable Materials S O U R C E : U . S . Department of Energy, Alternative Feedstocks Program Assessment, July 1993

Hemicelluloa

•J Cellulose [•


XYLITOL FURAN TETRA HYDROFU RAN FURFURYL ALCOHOL

PERACETIC ACID

ACRYLIC ACID

LEVULINICACID

5-HYD ROXYMETHYL FURFURAL

GLUCONIC ACID

MANNITOL

SORBITOL

i

I-

>


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Alternative Feedstocks and Processes. The chemical industry is beginning generally to review the feedstocks and processes that they have historically used in the manufacture of some of their most basic products. Monsanto has begun to institute changes in the way the company makes aromatic amines (35,36). Rather than proceed through a route that necessarily generates and utilizes chlorinated aromatics, many of which have been identified as posing environmental hazards, Monsanto is developing a method of direct amination of nitrobenzene via nucleophilic aromatic substitution of hydrogen. In addition, Monsanto is also pursuing methods of making urethanes and isocyanates without the use of the acutely toxic phosgene by replacing it with carbon dioxide (37). DuPont is using Just-In-Time manufacturing methods which incorporate in situ generation techniques to minimize the risk of exposure to hazardous substances (14). These techniques have been applied to processes which use particularly toxic substances such as methylisocyanate in an agrochemical process. This example illustrates efforts being pursued in basic research both in academia (described above) and in industry in developing environmentally benign masked synthons. Some widely used materials in the chemical industry are also commonly recognized as posing significant hazard. Fluorinating agents such as H F , FC10 and C F O F are well known for both their efficacy and their hazards. Air Products has developed a fluorinating reagent which requires no special handling and performs selective fluorinations on a wide variety of substances. Selectfluor (38), or 1chloromethyl-4-fluoro-1,4-diazonia[2.2.2]bicyclooctane bis(tetrafluoroborate), is an example of product development which includes both effectiveness and environmental considerations. 3

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Governmental Initiatives and Public/Private Partnerships The goals of pollution prevention complement many of the strategic goals of the United States. It is obvious that the national goals of environmental protection as reiterated in the Pollution Prevention Act are served by this relatively new focus of the environmental movement. However, it is also true that interests of the country's economic competitiveness, health and well-being of the nation's populace as well as its basic science and research capabilities are also beneficiaries of this new pollution prevention policy. It is for these reasons that there is such a wide spread support for more environmentally benign processes to be developed throughout all sectors of the economy and the scientific community. U . S . Environmental Protection Agency. In the earliest days of the Pollution Prevention movement, the U.S. E P A ' s Office of Pollution Prevention and Toxics began the pursuit of the concept of using alternative synthetic pathways for pollution prevention. The E P A structured a model funding program which would promote Benign By Design chemistry in the development of new synthetic methodologies. This program was designed to serve as demonstration to both the scientific community as well as the major scientific research funding agencies, that this type of research was viable, productive and necessary. The initial six grants provided ample justification for further funding and served as a vivid illustration of the type of fundamental research that can be accomplished in this area. This initial effort


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was the forerunner to the large number of programs which are pursuing the goal of designing chemical syntheses to achieve pollution prevention.


Benign Synthetic Design Tool Development. The E P A is engaged in the development of a number of tools in the form of guidance, computer software, and evaluation protocols to assist the synthetic chemist in designing benign reactions. As discussed previously the E P A is promoting the incorporation of environmental considerations into synthetic software programs such that when various synthetic pathways are generated, a listing of environmental impacts is presented to the chemist to consider. Guidance and Evaluation Protocols. As part of the E P A ' s Office of Pollution Prevention and Toxics New Chemicals Program there has been developed a procedure which reviews new chemical substances entering United States commerce for "unreasonable risk to human health and the environment." As part of this program, a Benign By Design Chemistry review has been instituted to review the manufacturing process. This review, Synthetic Methodology Assessment for Reduction Techniques (SMART) (39) provides suggestions to the chemical industry for ways to incorporate more benign methods of making, processing or using chemical substances. The review procedure is to be converted into a guidance manual such that the regulated community can use the protocols in evaluating both their new and existing manufacturing processes. Curriculum Development. The skill of incorporating environmentally benign synthetic techniques into the manufacturing processes of the chemical industry will be required well into the foreseeable future. In order to make these pollution prevention approaches a systematic part of doing business, industry is going to need to be equipped with a workforce that has been trained in Benign By Design Chemistry. For these reasons, the E P A has promoted the development of educational materials which will train chemists at various levels of their education in considering environmental impacts. The materials will include: • Textbook supplements which parallel the classical chemistry texts but offer environmentally benign alternatives to standard techniques; • A reference module for faculty which allows them to easily translate latebreaking environmentally benign research into their classroom presentations; • Laboratory modules which illustrate the experimental principles of benign chemical synthesis through undergraduate lab experiments; and, •

Professional training for industrial bench chemists to address why pollution prevention is desirable for a company and how environmentally benign chemistry can achieve it.


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Environmental Technology Initiative. The current Administration launched a program to promote the development of innovative technologies which address environmental problems. The Environmental Technology Initiative (ETI) was begun in 1993 and designed to provide funding which will facilitate the generation and utilization of environmental technologies through research, development, information dissemination and removing regulatory barriers. This program includes, as one aspect, the development of more environmentally benign synthetic chemistry methodologies. The EPA acts as a steward for the funding and sets criteria by which funding can be distributed to other Federal or State agencies as well as public/private consortia. National Science Foundation. As a major funding institution for basic research in chemistry including chemical synthesis, the National Science Foundation (NSF) has identified environmental considerations in designing synthetic methodologies as an area that warrants support and funding. Through the use of a special program for funding developed in the Division of Chemistry by Dr. Kenneth A. Hancock entitled "Environmentally Benign Chemical Synthesis and Processing Program," the NSF is seeking to promote the use of environmentally friendly methods in chemical manufacturing through the discovery of innovative chemical technology. The NSF developed this program in concert with the Council for Chemical Research (CCR) and established a Memorandum of Understanding in January of 1993 with the EPA to work collaboratively in promoting benign chemistry. The NSF also has promoted benign chemical manufacturing through the use of its Industry/University Cooperative Research Centers Program. An example of one of these centers would be the Emission Reduction Research Center housed at the New Jersey Institute of Technology (NJTT). This collaboration between academic institutions such as NJTT, Massachusetts Institute of Technology, Ohio State University and Pennsylvania State University with several specialty chemical and pharmaceutical companies and Federal agencies such as NSF and EPA provides a useful venue for conducting research on environmentally benign manufacturing methods and ensuring that the research fits the needs of industry and society. Department of Energy. As part of its historical charge toward exploring all aspects of energy efficiency and general energy utilization, the Department of Energy (DOE) has focussed much attention on the environmental impacts of various technologies. In its program, Environmentally Conscious Manufacturing, DOE works with a wide range of companies from many industrial sectors. In addition, the National Laboratories are actively pursuing research in environmentally benign chemistry. As an example, Los Alamos National Laboratory has established a partnership with the U.S. EPA's Office of Pollution Prevention and Toxics in investigating the use of supercritical fluids as a synthetic reaction medium. This collaborative effort includes private companies as well as universities and serves to illustrate an approach to conducting fundamental research which can be geared to both the need for technological innovation and environmental responsibility.


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Future of Benign By Design Chemistry A workshop was convened jointly by the U.S. EPA and the NSF entitled "Green Syntheses and Processing in Chemical Manufacturing" (40). Here, experts in the field of chemical synthesis from academia, industry and government were asked to identify the needs, in terms of research and implementation, which have to be addressed in order to accomplish the incorporation of environmentally benign chemistry in the chemical manufacturing industry. Many of the statements of need are very specific while others are quite global in their scope. Some of the suggestions identify work currently being done which needs to be identified and applied to environmentally benign applications. The list below should not be viewed as comprehensive by any means, but rather as a thought-provoking starting point. • Identify a list of the top processes that provide opportunities for pollution prevention; • Include benign chemistry as a core tenet of the chemistry curriculum; make responsible chemistry as important as creative chemistry. • Develop robust homogeneous oxidants; • Develop safer solvents to replace current ones - or use solventless systems; • Use selective clean oxidative functionalization (bond making processes) in order to reduce the use of substitution processes; • Develop and promote the use of solid acid catalysts (heterogenizing processes); • Design processes for the recovery of reagents - develop new separation techniques; • Investigate novel media and/or reaction systems to enhance selectivity of chemical transformations; • Develop educational approaches to familiarize synthetic chemists with separations and processes (physical/chemical isolation); • Develop an valuative tool to assess environmental impact of synthetic methods on both the bench and process scale; • Develop a means of funding interdisciplinary teams of scientists to collaborate on addressing key problems in research and education; • Develop a database/information network on benign synthesis; • Conduct research on small molecule biomimetic catalysts;


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BENIGN BY DESIGN

• Develop catalysts capable of complex reactions by multi-step transformations at a single site; • Develop functional mimics of enzymes; • Investigate means to increase enantioselective synthetic methods (particularly catalysis); • Promote investigations in biocatalysis, enzymatic, and microbiological


transformations; • Promote photochemistry and electrochemistry for benign synthesis; • Investigate the use of supercritical fluids in catalytic and biocatalytic reactions; • Investigate molecular design for advanced separations; • Design target molecules which preserve the desired function while mitigating toxicity by structural as well as physical/chemical property modification; • Develop, among synthetic chemists, a functional group understanding of health and environmental hazards; and • Investigate the use of renewable feedstock alternatives to petroleum. Conclusion Synthetic chemists have an important and fundamental role to play in the environmental movement. Because of their training, knowledge, and expertise, they are the only people capable of designing chemical syntheses at the front-end to ensure that environmental impacts are minimized. As mentioned previously, Benign By Design Chemistry is not a panacea that will solve the world's environmental problems. There are numerous situations where other pollution prevention solutions or even pollution control measures may need to be employed due to cost or logistical considerations. However, Benign By Design Chemistry should be the option of first choice which is built into the earliest stages of planning to manufacture a chemical product in order to ensure full consideration of the most fundamental pollution prevention methods available. Acknowledgments I would like to express my sincere gratitude and appreciation to Dr. Roger L. Garrett for his foresight and vision in establishing the Alternative Synthetic Pathways for Pollution Prevention Project and for putting his faith in a young chemist to develop the program.


1. ANASTAS


21

Disclaimer

This chapter was prepared by Paul Anastas in his private capacity. No official support or endorsement of the U.S. Environmental Protection Agency is intended or should be inferred. Literature Cited 1. Underwood, J.D. EPA Journal 1993, 19(3), pp 9-13. 2. U.S. EPA. 1992 Toxics Release Inventory: Public Data Release; Downloaded by BROWN UNIV on May 8, 2016 | http://pubs.acs.org Publication Date: November 18, 1994 | doi: 10.1021/bk-1994-0577.ch001

EPA 745-R-94-001; U.S. EPA: Washington, DC, 1992. 3. Dow Chemical Company. Environmental Health & Safety Milestones: Dow's History of Commitment. undated, Cited In U.S. EPA. Pollution Prevention 1991: Progress on Reducing Industrial Pollutants; U.S. EPA:

Washington, DC, 1991, EPA 21P-3003;p58. 4. 3M. 3M's Pollution Prevention Pays. Environmental Engineering and

Pollution Control Dept./3M: St. Paul, MN, undated. 5. Pollution Prevention Act of 1990. 42 U.S.C. §§13101-13109, 1990. 6. Browner, C . M . EPA Journal 1993, 19(3), pp 6-8. 7. U.S. EPA. Pollution Prevention 1991: Progress on Reducing Industrial

Pollutants; EPA 21P-3003; U.S. EPA: Washington, DC, 1991, pp 83-

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14. Illman, D.L. Chem. Eng. News 1993 (Sept. 6), pp 26-30. 15. Woods, M. Sacramento Bee 1993 (August 26),pA18. 16. Business Week 1993 (August 30), 3334,p65.

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pp 902-910. 21. Jorgensen, W.L.; Laird, E.R.; Gushurst, A.J.; Fleicher, J.M.; Gothe, S.A.; Helso, H.E.; Padreres, G.D.; Sinclair, S. Pure Appl. Chem. 1990, 62, pp 1921-1932. 22. Corey, E.J.; Long, A.K.; Rubenstein, S.D. J. Org. Chem. 1985, 228,

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25. DeSimone, J.M.; Maury, E.E.; Menceloglu, Y.Z.; McClain, J.B.; Romack, T.J.; Combes, J.R. Science (Washington, D.C.) 1994, 265, pp 356-361. 26. Tanko, J.M.; Blackert, J.F. In Preprints of Papers Presented at the 206th ACS National Meeting, Chicago, IL, August 22-27, 1993; Elzerman,

A.W., Chairman; American Chemical Society: Division of Environmental Chemistry: Milwaukee, WI, 33(2); pp 313-15. 27. Tumas, W.; Feng, S.; LeLacheur, R.; Morgenstern, D.; Williams, P.; Buelow, S.; Burns, C.; Foy, B.; Mitchell, M.; Burk, M.; Waymouth,


R.; In Preprints of Papers Presented at the 208th ACS National Meeting,

Washington, DC, August 21-25, 1994; Bellen, G.E., Chairman; American Chemical Society: Division of Environmental Chemistry: Milwaukee, WI, 34(2); pp 211. 29. Draths, K.M., Ward, T.L.; Frost, J.W. J. Am. Chem. Soc. 1992, 114, pp 9725-9726. 30. Alternative Feedstocks Program Technical and Economic Assessment;

Bozell, J.J.; Landucci, R., Eds.; U.S. Department of Energy: Boulder, CO, 1993; pp 211-217. 31. Kraus, G.A.; Kiriyuki, M.; Wu, Y. In Preprints of Papers Presented at the 206th ACS National Meeting, Chicago, IL, August 22-27, 1993;

Elzerman, A.W., Chairman; American Chemical Society: Division of Environmental Chemistry: Milwaukee, WI, 33(2); pp 330-331. 32. Epling, G.A.; Wang, Q. In Preprints of Papers Presented at the 206th ACS National Meeting, Chicago, IL, August 22-27, 1993; Elzerman, A.W.,

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Chairman; American Chemical Society: Division of Environmental Chemistry: Milwaukee, WI, 33(2); pp 328-329. Cusamano, J. CHEMTECH 1992, 22, pp 482-489. Chemicaoggi 1992 (Mar.), pp 44-45. Stern, M.K.; Bashkin, J.K.; U.S. Patent 5117063A, 1992, to Monsanto. Stern, M.K.; Hileman, F.D.; Bashkin, J.K. J. Am. Chem. Soc. 1992, 114, pp 9237-9238. McGhee, W.D.; Riley, D.P. Organometallics 1992, 11, pp 900-907.

38. Lal, G.S. J. Org. Chem. 1993, 58(10), pp 2791-6.

39. See chapter in this book by Farris, C.A.; Podall, H.E.; Anastas, P.T. 40. U. S. EPA. Proceedings: Workshop on Green Syntheses and Processing in Chemical Manufacturing, Cincinnati, OH, July 12-13, 1994; U.S. EPA:

Cincinnati, OH, 1994, in press. RECEIVED September 13, 1994


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